D-instantons in Type IIA string theory on Calabi-Yau threefolds

TL;DR

This paper computes non-perturbative D2-brane corrections to the hypermultiplet moduli space in Type IIA string theory on Calabi-Yau threefolds using a direct world-sheet approach, confirming previous predictions without relying on dualities.

Contribution

It introduces a direct world-sheet method to calculate D-instanton corrections, avoiding reliance on duality symmetries or supersymmetry assumptions.

Findings

Results match earlier predictions from duality-based methods.

Provides explicit calculations of corrections in each homology class.

Confirms the validity of the direct world-sheet approach for non-perturbative effects.

Abstract

Type IIA string theory compactified on a Calabi-Yau threefold has a hypermultiplet moduli space whose metric is known to receive non-perturbative corrections from Euclidean D2-branes wrapped on 3-cycles. These corrections have been computed earlier by making use of mirror symmetry, S-duality and twistorial description of quaternionic geometries. In this paper we compute the leading corrections in each homology class using a direct world-sheet approach without relying on any duality symmetry or supersymmetry. Our results are in perfect agreement with the earlier predictions.